In today's world, an Internet user may have numerous accounts with online service providers (e.g., online vendors, digital streaming providers, news outlets, etc.). Unfortunately, once a user creates an account with an online service provider, there is no mechanism for controlling the extent to which the online service provider shares the user's account information with other entities. Furthermore, when an online service provider has shared the user's account information, there is no mechanism for users to identify which of the online services he or she subscribes to has shared the account data. The instant disclosure, therefore, identifies and addresses a need for improved systems and methods for detecting unauthorized data shares (e.g., for identifying online entities that share users' account data with other entities).